Physics aims to figure out the rules that govern the reality we all share. Once inferred, the laws of physics cannot be broken. A specific elementary particle, like a particular electron, cannot choose to violate the laws of electrodynamics and take a path that no other electron took before.
The physical laws rule throughout all observable space and time. Electrons in terrestrial laboratories — 13.8 billion years after the Big Bang, appear to follow exactly the same laws as electrons in the hot dense soup of elementary particles that filled the Universe merely 400 thousand years after the Big Bang. The latest data on the cosmic microwave background implies that the recombination of electrons with protons followed the same behavior as measured on Earth to within percent-level accuracy, long before life started on Earth.
The physical reality did not have to be that strict, but it is. There is no free will in the elementary particle domain. However, it is well known that when human societies decide about a set of laws, some of their members choose to violate these laws. This outcome is surprising because the human body is made of elementary particles which do not possess that freedom. One way to understand the unpredictability of human behavior is through the complexity of the human brain. This interpretation could be tested experimentally soon. Once artificial intelligence (AI) systems will possess the same number of parameters as the number of synapses in the human brain, they might exhibit a similar level of unpredictability as the humans do. In that case, free will is simply an emergent phenomenon stemming from the complex architecture of the human brain. That the behavior of a large collection of elementary particles appears unpredictable should not be surprising given that even a three-body system in Newtonian dynamics shows chaotic behavior, with small deviations in initial conditions causing divergent outcomes. Free will may just be an amplified representation of the “butterfly effect” in the highly nonlinear architecture of the human brain.
The ability of humans to violate societal laws has two implications. First, societal laws are optional and spacetime dependent. They could be different on Earth than they are on an exoplanet. They are different today than they were a thousand years ago. In fact, these laws did not even exist 400 thousand years after the Big Bang. Second, as these laws can be violated, there is a need for a judicial system that assigns punishments to criminals who violate societal laws. There is no need to police electrons because they never violate the laws of quantum mechanics.
Our court system disciplines individuals based on eyewitness testimonies. However, science relies on repeatable measurements by instruments. If a new phenomenon represents new physics, then by repeating the same circumstances that led to it, any observer would find the same outcome. There is no need for a court, because the physical reality can be reliably characterized by data from instruments which avoid the weaknesses of the human mind, such as wishful thinking and hallucinations.
For this reason, I was surprised to be contacted yesterday by a group of people who would like to vet the physical reality in the courtroom. They wish to hear eyewitness testimonies about Unidentified Anomalous Phenomena (UAP) and let a judge rule if these phenomena truly exist in the physical reality that we all share. They argue that if multiple witnesses repeat the same story, the jury might find the evidence compelling. In my conversation with a representative from this group, I tried to explain that this is not the correct path for figuring out physical reality.
UAP were reported by the office of the Director of National Intelligence and by the All-Domain Anomaly Resolution Office (AARO) in the Pentagon, and were described through testimonies under oath in recent congressional hearings. Eyewitness testimonies about UAP should motivate programs like the Galileo Project that construct observatories to collect scientific data on UAP in order to figure out their nature. However, human testimonies by themselves are not sufficient to suggest new physics. For that, one needs exquisite data collected by well-calibrated instruments.
FIFA referees use data from video cameras on the soccer field, because eyewitness testimonies by players or the audience may be biased. The beauty of science is that everyone can serve as the referee once data from instruments is made public. Such data characterizes the underlying physical reality and not our personal impressions of it. The benefit of scientific data over eyewitness testimonies is apparent from the fact that there were 34 cases over the past three decades across 15 US states of people who have been exonerated from death row with DNA evidence. These cases represented 17% of the 200 death row exonerations.
Of course, scientists are humans and they could be inspired to follow the scientific method by their emotional response to the physical reality. A couple of days ago, the brilliant astronomer Kelsey Johnson spoke about the importance of awe in science at Harvard’s Institute for Theory & Computation for which I serve as director. I noted to Kelsey that astronomers are fortunate because the Universe offers scales and extreme conditions that are not realized on Earth. Astronomical studies are perfect opportunities to be filled with awe.
If some UAP ends up being extraterrestrial technological gadgets, they might inspire awe, perhaps even religious awe, akin to witnessing the product of a superhuman intelligence. In that case, we will have an opportunity to expand our century-old knowledge base in science and technology.
Last week, I saw a giant turtle which is 150 years old in Richard Branson’s Necker Island. It occurred to me that this turtle was born in the 19th Century and lived through all the milestones of modern science. With the benefit of a billion years of science, an advanced extraterrestrial civilization might appear like this giant turtle on steroids.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
